"This is my kind of deal and my kind of partner," Buffett said on CNBC's "Squawk Box" shortly after the deal was announced. "Heinz is our kind of company with fantastic brands."

Judged by some metrics, this doesn't look like a bargain-hunter's move. Heinz trades at a 15-percent premium to its five-year historical P/E of 16.5.

Jeff Matthews, a Berkshire Hathaway shareholder and author of "Secrets in Plain Sight: Business and Investing Secrets of Warren Buffett," says that Buffett has adjusted his investment strategy as his company transformed into a global conglomerate.

"This is not your father's Berkshire," Matthews says.

Decades ago, Buffett worked as a value investor, buying stocks that he judged cheap and waiting for the market to catch up. Today, to keep Berkshire growing, Buffett can no longer rely on a basket of stocks. He needs to buy a basket of companies, which he bets will grow over time.

Buffett's Berkshire Hathaway is buying Heinz for $23 billion, and U.S. Airways and American Airlines have officially merged to form the world's biggest airline. CNBC's Phil LeBeau and Brian Shactman have the details. Jonathan Feeney, Janney Montgomery Scott, weighs in.

Paul Hickey of Bespoke says the low interest rate and low growth environment makes the Heinz acquisition a "no brainer" for a guy like Buffett, with lots of cash on hand.

"It's not a real exciting company, but it's pretty much as stable as they come. They've been constantly raising their dividend. Through the financial crisis, they raised their dividend each year. It's almost like a bond in that it's paid such a consistent dividend," he said. (Read More:Berkshire Hathaway's 15 Biggest Stock Holdings)

Vitaliy Katsenelson, CIO of Investment Management Associates, points out that Buffett increasingly considers his legacy when making investment decisions. The Oracle of Omaha, he says, is willing to pay a "legacy premium"—more money for companies that he believes will benefit Berkshire—and his reputation—long after he retires.